What is the most important information I should know about warfarin (Coumadin)?

Follow your doctor's instructions about taking warfarin while you are pregnant. Warfarin can harm an unborn baby or cause birth defects. However, the benefits of preventing blood clots in certain women may outweigh any risks to the baby.

Never take a double dose of this medication.

You should not take warfarin if you have a bleeding or blood cell disorder, blood in your urine or stools, an infection of the lining of your heart, stomach bleeding, bleeding in the brain, recent or upcoming surgery, or if you need a spinal tap or spinal anesthesia (epidural).

Warfarin may cause you to bleed more easily, especially if you have: a history of bleeding problems, high blood pressure or severe heart disease, kidney or liver disease, cancer, surgery or a medical emergency, a disease affecting the blood vessels in your brain, a history of stomach or intestinal bleeding, if you are 65 or older, or if you are severely ill or debilitated.

Many drugs (including some over-the-counter medicines and herbal products) can cause serious medical problems or death if you take them with warfarin. It is very important to tell your doctor about all medicines you have recently used.

Ask your doctor before taking any medicine for pain, arthritis, fever, or swelling. These medicines may affect blood clotting and may also increase your risk of stomach bleeding.

Any doctor, dentist, surgeon, or other medical care provider who treats you should know that you are taking this medication.

Avoid making any changes in your diet without first talking to your doctor.